Zope: 5.7 → 5.7.3
-----------------

Security fix for a Cross Site Scripting vulnerability.
See https://community.plone.org/t/zope-4-8-4-and-5-7-1-released/15992


plone.protect: 4.1.7 → 4.1.8
----------------------------
Bug fixes:

- Testing: explicitly set response content type header to html.  [jeromeperrin] (#97)


plone.volto: 4.0.2 → 4.0.4
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Bug fixes:

- Clarifications in the @@migrate_to_volto wizard. Volto is a separate service that needs to be configured and hosted. It is not included in the Plone backend.
  Editing the main content that was in RichText fields before will no longer be possible after migration.
  Fix link to Volto frontend documentation.
  [fredvd, stevepiercy] (#106)

- Fix a11y problems in both demo and default pages @sneridagh (#105)